Petrolatum sulfonate



Patented Feb. 18, 1947 PETROLATUM SULFONATE Richard W. Mertes, Los Angeles, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application February 20, 1943, Serial No. 476,651

Claims. 1

This invention relates to the production of sulfonic acids and their salts, especially the calcium sulfonate from hydrocarbon mixtures containing petrolatum.

In the past, sulfonic acidsgenerally have been produced commercially by the reaction of fuming sulfuric acid on liquid hydrocarbons such as mineral oils. For example, they have been obtained as by-products in the manufacture of white oils or medicinal oils, in which process a lubricating oil is treated with fuming sulfuric acid in sufficient quantity to remove substantially all of the coloring matter normally present. According to one conventional procedure employed the sludge resulting from this treatment is allowed to settle and is then drawn off. The treated oil is then washed with water, which is generally discarded, and finally with caustic soda solution. The caustic dissolves the sulfonic acids remaining in the oil and converts them into sodium sulfonates which may be subsequently converted to sulfonates of other metals by familiar methods of metathesis. More recently it has been found that other liquid mineral oil fractions, such as certain petroleum lubricating oil fractions which are not too highly refined, may be sulfonated by methods somewhat analogous to the above with good yields, of sulfonated product. Sulfonation of solid hydrocarbons however, such as paraflin wax, by similar treatment with strong sulfuric acid, has given only a trace of sulfonated product.

It has now been discovered that another type of solid hydrocarbon, namely petrolatum, or hydrocarbon mixtures containing petrolatum, may be readily sulfonated to give in many instances the highest yields of hydrocarbon soluble soaps of any naturally occurring petroleum fraction yet tested, yields which may be hundreds or thousands of times greater than those obtained with ordinary crystalline paraffin wax under the same conditions. Furthermore, certain products obtained from the sulfonation of petrolatum or mixtures containing petrolatum are unique in some respects and superior in nearly every respect, particularly for use in compounded oils, to the corresponding products from other stocks.

To illustrate the difference between petrolatum I and other fractions from the same crude oil, let

the desired viscosity. This crude fraction may be first dewaxed by treatment with propane at low temperatures. The dewaxed oil may then be given a moderate treatment with a selective solvent such as phenol, to obtain two fractions, a raflinate fraction of about 80 viscosity index, and the corresponding extractfraction. The slack wax obtained in the above dewaxing step may then be deoiled by treatment with methylethyl ketone at low temperatures to obtain two fractions, one a crystalline paraffin wax and th other a foots oil having a melting point of 90 F. to 110 F. Thus, the original vacuum distillate by the above procedure may be separated into the four indicated fractions, all of which have about the same average molecular weight. For brevity these fractions will be termed merely raffinate, extract, wax and petrolatum. Upon evaluating these materials as sulfonation stocks according to (1) yield of sulfonate and (2) quality of the calcium sulfonate concentrate prepared therefrom by the preferred sulfonation' process described later, the following data may be obtained:

Table 1 Vis 9? Deter D0111 K y, index a F. per cent figilnrg Base oil alone 5. A. E. 30 90 20 11 Base oil plus sulfonate concentrate from- Rafiinateyield=3.5% 92 20 23 Extract-yield=l% 65 20 45 7 Waxyie1d=.002%..... Petrolatum-yicld=5% 95 0 30 In the above tabulation the yield figures are not percentage of each stock sulfonated, but are believed to be proportional thereto, since they are the CaSOr ash contents of the calcium sulfonate concentrates. These concentrates contain appreciable amounts of unsulfonated hydrocarbons, which are also included in the above blends. Similar effects would be observed also if the unsulfonated hydrocarbons were eliminated, or if a different type of base oil were used in the blends.

In the determination of theCaSOi ash, about two to ten grams of the concentrate is weighed into a tared crucible, the crucible and contents are heated and the hydrocarbons are ignited, a1- lowing the combustible material to burn slowly, igniting the residual ash to free it of carbon, adding a few drops of concentrated sulfuric acid to convert any reduced calcium sulfide, etc., to sulhave an unctuous, grease-like texture. j iar forms of petrolatum in a refined state are the materials known commercially as Vaseline" and fate, re-igniting, and weighing the residue, which 1 is reported as (32504 ash in'percent of the concentrate tested. It is obvious that this is a reasonably good measure of the degree of sulfonaj tion obtained, and that the petrolatum is an out- 1 standing stock in this respect.

The quality of the calcium sulfonate from the 1 petrolatum is also outstanding,.as shown in the tabulated data. In this work, enough of the calcium suifonate concentrate from each stock is 1 added to the given base oil to obtain a product having a CaSO4 ash of 0.42%. tested for pour point and for viscosity at 100 This product is F. and 210 F. by familiar A. S. T. M. methods,

combustion (Lauson) engine equipped with copper-lead bearings which are notoriously sensitive to corrosion in this type of service. The bear- 1 ings are weighed after each hours of service and if the weight loss exceeds about 150 mg. bei fore 60 hours of service has elapsed, they are.

replaced by Babbitt bearings. The run is dis-' is a type of pseudo-petrolatum of lower molecular weight and lower melting point. (The molecular weight, however, is preferably not less than the average molecular weight of an S. A. E. 30

continued at the end of 60 hours, the engine is dismantled, and the general cleanliness of the inside crown of the piston, inside wall of the 1 piston, the skirt, ring grooves, ring lands, and

oil ring slots is noted. The tabulated anti-corrosion figures are interpolated values for the number of hours of operation at the time at which the bearings had lost 100 mg. in weight,

while the detergency figures indicate the clean liness of the engine at the end of the run, 100% being the rating of a perfectly clean engine, and 0% that of the worst possible condition of every one of the above described parts. It is apparent that the petrolatum yields a sulfonate which is outstanding in its effects on viscosity index, detergency, and anti-corrosion, as well as unique in its effect on pour'point.

It is an object of this invention to provide a hydrocarbon sulfonation stock and a sulfonation l processby means of which sulfonates of special quality, particularly for use in lubricating oils,

= may be produced.

Thesulfonation stock of this invention comprises petrolatum by which term is meant to include fractions from petroleum, shale, etc.,

which contain a sufl'icient proportion of normally 1 solid hydrocarbons to have melting points above 1 room temperature (above 80 F.) and which do not have ,a distinctly crystalline structure, but

Familwhite petroleum jelly. Another form which is I to ,be included in our definitition of petrolatum be considered as the heavy unctuous material of high molecular weight and high melting point which generally appears in petroleum residua,.

lubricating oil distillate.) Both of these types of petrolatum, as defined above, contain normally solid hydrocarbons which difier from the well known varieties of crystalline wax in that they are-amorphous or at least micro-crystalline in character, and when sulfonated and neutralized as described later, the resulting calcium sulfonates are obtained in exceptionally high yields, and have the unusual property of pour point depressing action as well as exceptional detergency, anti-corrosion and V. I. improving action.

The process by which the above stocks may be sulfonated may include three steps, namely (1) pre-treatment of the stock, which is described below, (2) the sulfonation proper, which may involve treatment with concentrated sulfuric acid, chlorsulfonic acid, sulfuric acid plus absorbing agents, such as phosphorus pentoxide, etc" and (3) recovery of the sulfonic acids, which may involve neutralization and recovery of the soaps. The preferred method, however, involves suitable pre-treatment of the stock followed by treatment with concentrated sulfuric acid and subsequent neutralization of the reaction product with an excess of the desired neutralizing agent such as caustic soda or lime. This differs from the conventional process utilized in the past in that the more water-soluble green sulfonic acids, which in the conventional process dissolve in. the acid sludge and the wash water and are not normally recovered therefrom, are converted to soaps which largely remain dissolved in the hydrocarbon phase together with the soaps of the more oil-soluble mahogany sulfonic acids. This not only increases the yield of sulfonic acid soaps, but apparently improves the efiectiveness of the sulfonates as lubricating oil additives. Furthermore, it, is obvious that by elimination of the steps of sludge withdrawal and water washing, not onlyis there a'substantial economy achieved, but the possibility of-contamination of the product with iron or lead salts picked up by the action ofthe acidic materials on the equipment, is avoided. This contamination may be very deleterious especially for sulfonates to be used in lubricating oils.

After adding the excess neutralizing agent, the reaction mixture, plus an oil-soluble diluent if desired, is settled and centrifuged or filtered to remove the solid reaction products insoluble in the oil. If a diluent has been added, it is separated atthis point, leaving the soap dissolved in the oil as a sulfonate concentrate. It has been found that when the sulfonation stock contains moderately pre-acid treated petrolatum, the solid insoluble reaction products generally separate with. unusual ease.

In order to minimize loss of green acids in the water formed in the neutralization reaction or added with the neutralizing agent, the aqueous phase separated in the settling, centrifuging, tc..-

Table 2 Detergency, Anti-corroper cent sion, hours Base oil alone 60 11 Base oil+calcium sulfonatejrom foots 011 petrolatum pretreated with- 115 1b. H2804 per bbl. y1e1d=7% 55 15 165 lb. H1304 per bb1.yield=% 80 30 215 lb. H2804 per bbl. y eld=5% 80 24 265 lb. H2804 per bbl. yield=4% 70 20 These data show the value of a moderate degree of pretreatment, such as about 125 to 275 pounds of 95% sulfuric acid per barrel and preferably about 150 to 200 pounds per barrel. The degree of pretreatment is not always so critical as the above data indicate, however, when other stock such as true petrolatum are considered. For example, a crude untreated dark true petrolatum obtained from a Utah crude'oil may be sulfonated without pretreatment to obtain a product which is approximately comparable in quality to the 115 pound H2804 pretreated foots oil petrolatum sulfonate of Table 2 and is obtained in about the same yield, the CaSO4 ash of the concentrate being 7%. Pretreatment which is very severe, however, may reduce this yield of sulfonate somewhat. For example, a true petrolatum from a Mid-Continent crude oil which has been subjected to pretreatment with the equivalent of about 500 pounds of 95% sulfuric acid per barrel of strong sulfuric acid may be sulfonated by the same method to obtain a sulfonate concentrate having a CaSO4 ash content of only about 3% and approximately comparable in quality with the 215 pound H2SO4 pretreated foots oil of Table 2. Pretreatments with 95% sulfuric acid between the limits of about 50 to 500 pounds per barrel result in good quality products, and such treatments may be considered moderate for such stocks. The amount and strength of sulfuric acid or other reagent to be used for optimum effects will vary to some extent with the character of the stock to be treated, but in all instances it will be found that the optimum pretreatment is amoderate one, in that more or less pretreatment will tend to give a somewhat inferior product. Conditions of the pretreatment, such as temperature, etc., may be varied as desired as long as the resulting pretreatment is an equivalent one as defined below.

It is to be recognized that the equivalent treatment with selective solvents, such as sulfur dioxide, phenol, furfural, etc., or with polymerizing earths, zinc chloride, aluminum chloride, etc., may be substituted for part or all of the sulfuric acid pretreatment used for any of the above stocks. A convenient means of determining the equivalence of treatments with difierent reagents is the viscosity index of the treated product. For example, the viscosity'index of the foots oil petrolatum of Table 2, untreated, was 63 and after treatments with 115, 165, 215, and 265 pounds of sulfuric acid per barrel, this was raised to values of 104, 112, 117, and 119, respectively. It is apparent that for this stock the desired pretreatment with 95% sulfuric acid is one which will raise its viscosity index to about to 120, preferably to 115. Pretreatments of this stock with other-strengths of concentrated sulfuric acid or with the other reagents described above, which are carried out so as to yield products of corresponding viscosity index may be considered to be equivalent. Since this type of petrolatum contains an appreciable proportion (about to /2 in most instances) of normally liquid hydrocarbons, it is also possible to define the range of pretreatment in terms of the viscosity index of a liquid hydrocarbon fraction extracted from the pretreated entire petrolatum. For example, theviscosity index of the liquid fraction of approximately 0 F. pour point obtained by treatment of the above untreated foots oil petrolatum at 10 F. with 5 volumes of an equal volume mixture of methyl ethyl ketone and benzene, filtering the resultant mass, and evaporating the methyl ethyl ketone and benzene from the filtrate, was 28, and the viscosity indexes of the analogous oil fractions from similar treatment of this foots oil petrolatum with 115, 165, 215 and 265 pounds of 95% sulfuric acid per barrel were 54, 66, 80 and 85, respectively. The preferred pretreatment of this stock may therefore be defined as one which will raise the viscosity index of its content of oil of zero pour point to a value between about 60 and 80, and preferably about 65 to In the sulfonation of the stocks of Table 1, the foots oil petrolatum was pretreated with 165 pounds of 95% H2804 per barrel as described above. The selective solvent treatment given the dewaxed crude lubricating oil distillate may be considered as acomparable pretreatment of the raflinate of Table 1. The extract and wax fracand the temperature was allowed to rise to the boiling point of the carbon tetrachloride, about F., while the mixture was agitated thoroughly. After removal of the solids by settling, decanting, and filtering, the carbon tetrachloride was carefully distilled-off to obtain the finished calcium sulfonate concentrate.

In sulfonating the petrolatum of this invention, it is not necessary to use carbon tetrachloride as described above. It is desirable, however, to have the sulfonation stock in a rather fluid form which may be readily and thoroughly contacted with sulfuric acid. For this reason it may be desirable to warm the stock, or to dilute it with an inert material, such as carbon tetrachloride, chloroform, etc., or to sulfonate it in the presence of another more fiuid sulfonation stock. The temperature should not be allowed to exceed about 130 F. before the neutralizing agent is added, lest there be excessive decomposition, polymerization, etc., of the hydrocarbons, or excessive corrosion of the equipment. Agitation is generally continued for 10 to 30 minutes after adding the sulfuric acid before adding the neu- 7 tralizing agent. Shorter times of contact may be used, however, times as short as 0.1 second sufncing where there is sufllciently good contact. After the addition of the excess of neutralizing agent there is less danger of decomposition, etc., S. A. E. 40 waxy distillate of the original examand the temperature may be allowed to go higher, ples above may be given a moderate pretreatment but preferably not above about 170 F. The presand sulfonated by the preferred methods of this ence of carbon tetrachloride at this stage is of invention, and the sulfonates formed by lime neuparticular value, since allowing it to reflux at tralization of the product and the crystalline wax atmospheric pressure provides a convenient 10 may be separated from the residual oil by promeans of maintaining this temperature as a maxp treatment (the soaps may be pr f r n y imum. Instead of carbon tetrachloride other volrejected at atmospheric te p o b ve and atile materials which will reflux at about the separated, and he w p n lly rejected same temperature, such as a selected naphtha subseq n ly at sub-atmospheric temperature and out, etc., may be used, especially if added just be- Separated)- y Such a p s th WaXing is fore or just after the addition of the neutralizfacilitated by the conversion of the amorphous ing agent. Other diluents of different volatility W x to sulfonates; the sulfonates are prepared may l b used, and th means of temperain high concentration; and an optimum sulfonature control employed. Such added diluents pern Stock m y e ndedform an additional function in aiding the set- There is some e ce t t an pt mum sultling, filtration and/or centrifuging employed to fonation stock may be one which contains not separate the solid products. If soaps other than y petrolatum, il nd W but materials of calcium soaps are desired, neutralizing agents both high nd low ecular Weight the low other than lime may be used, with appropriate molecular weight materials still being in the range obvious modifications in technique, or they may f i ue oils, oweverb prepared by t th of t 11 soap i Modifications apparent to one skilled in the some instances. It is also possible, of course, to art are t be c ns dered part of the invention prepare the sodium soap by neutralization with as defined in t following c aims. caustic soda instead of lime, metathesizing this I claim: I product to the lime soap thereafter; or to prepare An improved lubricant which comprises a mixed soaps with two or more neutralizing major proportion of a lubricating O a a minor agents proportion sufficient to improve the service chart has b found t at th sulfonate eoneenacteristics of said lubricating oil of a sulfonate trates prepared by the above methods may be concentrate p p red by contacting a' hy a w' treated with a liquefied hydrocarbon gas such as 5 bon Stock Containing t least ut of p oprgpane t t rat r s b l w atm h ri t latum with a sulfonation agent, neutralizing the cause rejection of th soaps in relatively pure product with an alkaline neutralizing agent, and form from the oil-propane-rich solution. The Separating the q phase and the solid oil rejected soaps may then be separated, preferably insoluble reaction products from the resulting sulby settling, and readily freed of residual propane 40 fonate concentrate. or other volatile solvent by stripping. If desired 2. A lubricant according to claim 1 in which the this liquefied hydrocarbon gas may also be used alkaline neutralizing agent is lime. as the diluent added at about the time of addi- 3. An improved lubricant which comprises a tion of the neutralizing agent, this of course, remajor proportion of a lubricating oil and a minor quiring pressure operation. proportion sufiicient to improve the service char- No explanation is known for the unique properties of petrolatum as a sulfonationstock. It is known, however, that petrolatum," as defined above, may include mixtures of oils which are fluid below room temperature with hydrocarbons which are solid at room temperature. For example, the foots oil described above is known to contain both lubricating oil and solid pseudopetrolatum as well as an appreciable proportion of crystalline wax. Such mixtures may in many instances provide superior sulfonation stocks. For example, by separating foots oil into a lubricating oil fraction fluid at room temperature, and a solid fraction of higher melting point than the original foots oil, and separately sulfonating each of these fractions, it may be observed that the calcium sulfonate obtained from neither fraction is as eifective as the sulfonate from the entire original fraction, in reducing the pour point of a base oil to which it is added. Similarly, it may be observed in some instances that lubricating oil mixtures containing as little as about 10% of normally solid material having the characteristics of petrolatum exhibit some of the unusual properties of the petrolatum itself as a sulfonation stock. It is part of this invention, therefore, to include in the sulfonation stocks of this invention mixtures of viscous hydrocarbon oils containing at least about 10% of petrolatum. The presence of crystalline wax normally associated with the petrolatum is also desirable in some instances.

As an example of a process employing sulfonation of mixtures containing petrolatum, the

acteristics of said lubricating oil of a sulfonate concentrate prepared by contacting a hydrocarbon stock containing at least about 10% of petrolatum with concentrated sulfuric acid, neutralizing the entire reaction product with an excess of an alkaline neutralizing agent, and separating the aqueous phase and the oil insoluble reaction products from the resulting oil sulfonat'e concentrate.

4. A lubricant according to claim 3 in which the hydrocarbon stock is a foots oil petrolatum.

5. A lubricant according to claim 3 in which the alkaline neutralizing agent is lime.

6. A lubricant according to claim 3 in whichth petrolatum-containing stock is pretreated prior to its sulfonation, so as to remove therefrom constituents of undesirably low viscosity index, and thereby improve the quality and yield of the sulfonates produced therefrom. 7. An improved lubricant which comprises a major proportion of a lubricating oil and minor proportion sufiicient to improve the service characteristics of said lubricating oil of a sulfonate concentrate prepared by contacting a hydrocar- 70. bon stock containing at least about 10% of petrolatum with fuming sulfuric acid at a temperature below about F.; neutralizing the entire reaction product ata temperature below about F. with an excess of an alkaline neutralizing agent, 75 and separating the aqueous phase and the oil insoluble reaction products from the oil sulfonate 8. A lubricant according to claim 7 in which the sulfonation is carried out in the presence of an inert diluent.

9. A lubricant according to claim 7 in which the neutralization and separation steps are carried out in the presence of an inert diluent.

10. A lubricant according to claim 7 in whic the. alkaline neutralizing agent is lime.

concentrate.

The'following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Moser Sept. 10, 1940 Cobb Aug. 16, 1921 Robinson Aug. 16, 1921 Johansen Dec. 18, 1923 Cobb Mar. 26, 1929 Buc Apr. 2, 1929 Holmes Oct. 29, 1929 Gallagher Feb. 10, 1931 Steik Apr. 28, 1931 Frame June 25, 1940 Adams Jan. 13, 1942 Bergstr'om Jan. 20, 1942 Silverman' Jan. 12, 1943 Catanach "a--- Nov.28, 1939 

